线段

题目描述

思路

代码

#include <cstdio>

int n, ans, pre;
struct Node {
    int a, b;
} arr[1000006], tmp;
inline int read() {
    int s = 0, f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9') {
        if (ch == '-') f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9') s = s * 10 + ch - '0', ch = getchar();
    return s * f;
}
void qsort(int L, int R) {
    int l = L, r = R;
    int mid = arr[l + r >> 1].b;
    while (l < r) {
        while (arr[l].b < mid) l++;
        while (arr[r].b > mid) r--;
        if (l <= r) {
            tmp = arr[l];
            arr[l] = arr[r];
            arr[r] = tmp;
            l++, r--;
        }
    }
    if (l < R) qsort(l, R);
    if (L < r) qsort(L, r);
}
int main() {
    n = read();
    for (int i = 1;  i <= n; ++i) arr[i].a = read(), arr[i].b = read();
    qsort(1, n);
    for (int i = 1; i <= n; ++i) {
        if (pre <= arr[i].a) ans++, pre = arr[i].b;
    }
    printf("%d\n", ans);
    return 0;
}

原文地址：https://www.cnblogs.com/liuzz-20180701/p/11561946.html